Edible oils or fats are usually submitted to a number of process steps to transform the crude oil or fat into an elaborated product having a defined degree of purity, and defined organoleptic properties.
These refining steps can include degumming, neutralization, bleaching, active carbon treatment, filtering, distillation and/or deodorization.
In particular a deodorization step usually complements the refining of the oil or fat by removing the majority of the volatile substances. The undesired volatile substances, responsible for off-taste, and off-odours, are usually more volatile than triglycerides and can be removed by a deodorizing step.
In a conventional deodorizing step, steam is injected into the oil or fat at high temperature (usually between 175° C. and 270° C.) and low pressure (typically under a vacuum of below 5 mbar).
Refined edible oil or fat is usually used in a number of food products. Refined oils, and in particular palm oil or fish oil are typical examples. The oils such as palm oil provide functionality in the food product and deliver the necessary lipids in the diet while delivering a particular profile of fatty acids. Also the oils serve as carriers for numerous lipid-soluble nutrients such as some lipophilic vitamins or for a number of desired flavours. In infant formula, for example, vegetable oils can represent up to 50% of the energy of the infant formula.
The invention below will be described in the context of edible vegetable oils as a non-limiting way of illustration. The invention however encompasses edible oils and fats of all sources (vegetable oils, animal fat, fish oil, milk derived fat, etc. . . . ).
Edible oils and fats, and in particular vegetable oils, are highly susceptible to oxidation and may be an unfortunate carrier to lipophilic undesired flavors, odors or colored compounds. In particular it is often desirable to obtain fully refined and deodorized vegetable oil with a low level of free fatty acids. Being highly susceptible to oxidation, the free fatty acids, in particular polyunsaturated fatty acids, are known to induce undesired organoleptic properties. Similarly oils and fats can comprise a number of undesired molecules. The undesired compounds can be carried over from the crude oil and/or appear during the numerous processing steps of the oils: for example oils are often treated at high temperature. The combination of high temperature with the presence of particular compounds (e.g. oxygen or precursors of undesired compounds) can lead to finished oils having particular undesired compounds (generally referred to as “contaminants”).
While the aim of some process steps is to remove some undesired compounds, the same process steps can enhance the formation of other undesired compounds in the finished product. Hence a careful balance has to be found between desired effects and presence of undesired contaminants.
For example, in many instances it is desirable to purify the native palm oil in order to remove carotenoid molecules that are responsible for a brown/orange color. Indeed obtaining a limpid oil is often of importance for the visual quality of the finished product. Carotenoids are however best removed by a treatment at a relatively high temperature (e.g. heat bleaching). Such treatment at high temperature (typically above 200° C.), although necessary, can promote the oxidation of the oil and of contaminating molecules. In turn these molecules, oxidized, may create off-flavors. A balanced process is therefore necessary to mitigate all undesired chemical reactions while inducing the desired purification. The parameters of such processes are of high complexity (e.g. temperature, pressure, sequence, duration, added reactants, characteristics of the native oils or fats, equipment design, etc. . . . )
Monochloro propanediol esters (MCPD esters) have been identified as process-induced minor components in fully refined fats and oils. They are mainly formed during the deodorisation step. Two isomers at least have been shown to be formed, i.e. 2- and 3-MCPD esters, the latter being the predominant isomer. All fully refined fats and oils contain 2- and 3-MCPD esters; however, palm-based oils are generally oils with a relatively high content of 2- and 3-MCPD esters. While the exact formation process of the MCPD esters has not been totally understood, it has been observed that the temperature of the process, in particular the steam deodorization process, has a large impact: the higher the temperature, the higher is the amount of bound MCPD found in the vegetable oil. In particular temperature above 180° C., above 200° C., above 240° C. or above 270° C. induce respectively higher formation of bound MCPD.
Free 3-MCPD has been highlighted for its potential for adverse health effects and has been a subject of concern in regards to food products. It has recently been hypothesized that 3-MCPD esters could be at least partially hydrolysed into free 3-MCPD after ingestion. However there is currently no data indicating negative health effects of 3-MCPD esters (bound 3-MCPD) in food products. Nevertheless, in view of the potential for hydrolysis to free 3-MCPD, some authorities may regard bound MCPD as undesirable molecules in food products such as infant formula. It is of interest to monitor the levels of bound 3-MCPD in food products, especially infant formulae. Similarly it is of interest to investigate means to control the formation of bound 3-MCPD during the process steps used for the purification of edible oil or fat. By extension, similar considerations could in theory be applied to bound 2-MPCD.
Limiting the presence of bound 3-MCPD in the refined oils might be achieved by a careful selection of the oil or fat source or of the type of oil or fat used. However, the supply of material with low bound MCPD is uncertain and so far, no palm-based oil with guaranteed low levels of MCPD esters is commercially available.
Limiting the formation of bound MCPD during the process steps is another route to be explored.
There is a need to obtain an oil or fat that is low in bound MCPD while being free of other contaminants or undesired molecules.
There is a need for an edible oil or fat that is low in bound MCPD while being fully refined and deodorized. Such oil or fat has to have a neutral odour, and/or no off-taste, and/or a limpid aspect, and/or a low level in free fatty acids.
There is a need for an edible oil or fat that is low in bound MCPD while preserving all the other desirable lipo-soluble nutrients.
There is a corresponding need for a process that keeps the level of bound MCPD to a minimum level in the finished oil or finished product.
There is a need for a process of purifying an edible oil or fat that removes, or limits the formation, of bound MPCD or of precursors of bound MCPD.
There is finally a need for a process of purifying an oil or fat that leads to a low level of bound MCPD and has no off-odors and/or no off-taste and/or has a limpid aspect and/or has a limited level of free fatty acids.
In combination with the above needs, there is a need for obtaining oils or fats as described above and processes of making, that relates to a low level of bound 3-MCPD as bound 3-MCPD has been described as the MCPD compound of highest interest.